Radio apparatus



Jan. '3, 1928,, 1,655,243

- A.H.-ROSENTHAL RADIO APPARATUS Original Filed July 11, 1924 Amy [$01 941 IM'ENTOR Patented Jan. 3, 1928 UNITED STATES PATENT OFFICE.

AMBROSE H. ROSENTHAL, OF BROOKLYN, NEW YORK, ASSTGNOR TO OTTO MUNK,

TRUSTEE, OF NEW YORK, N. Y.

RADIO APPARATUS.

Application filed July 11, 1924, Serial No. 725,355. Renewed November 22, 1927.

My invention relates to radio apparatus and specifically to a piece of apparatus in the nature of a combined inductance and capacity which may be utilized for various purposes in the radio art.

The usual inductance coil comprising a primary and secondary winding and the common variable plate'condenser are well known in the art. The object of my inven tion is to combine them physically and elec trically in a manner to form a new piece of apparatus constituting a tuned impedance which will find a wide range of use in both transmitting and receiving sets and in the latter case will effect great improvements in the elimination of interference. I

A further object of my invention is to provide an inductance coil which may he used as an air-core transformer, whose primary and secondary windings may be tuned by means of one control.

A still further object is to provide a combined inductance and capacity in which the coil may be set at any angle with reference to the condenser whereby utilization as a transformer in connection with other transformers and instruments will be facilitated.

My invention consists of the construction and combination of parts fully described in this specification, set forth in the appended claims, and illustratively exemplified in the accompanying drawings, in which Figure l is a plan view of my apparatus;

Figure 2 is a side elevational view partly in section;

Figure 8 is a diagrammatical illustration of a possible mode of utilization.

Referring to the drawings, 10 denotes an induction coil of the usual type comprising two concentric hollow tubes upon which are wound primary and secondary windings. An inner tube ll has wound thereon a secondary coil (not shown), the terminals of which are binding posts 12 and 13 at opposite ends thereof. An outer tube 14: has Wound thereon a primary coil 15 the terminals of which are the binding posts 16 and 17. The primary is tapped at intervals along its length in the well known manner as indicated at 18, and leading off fromv these tapped exposed portions of the coil are wires 19, the other ends of which are attached to another portion of my instrument as will hereinafter be more fully described.

20 denotes a variable plate condenser of the usual type and construction comprising substantially triangular end members 21, a plurality of semi-circular spaced fixed plates 22 interposed between the end members a rotor shaft 23 and a plurality of spaced semicircular rotor plates 24 mounted on the rotor shaft and interposed between the fi ed plates in the usual manner. The end members 21 are bored to receive pins or rods 25 and the fixed plates are bored accordingly to align with the bores in the end members so as to allow the rods 25 to extend through and carry the fixed plates.

The rods 25 are securely fixed to one of the end members (for example the lower one in Figure l) and are externally threaded at their opposite ends to receive knurled nuts 26 which serve to bind the plates and the end members firmly together. In the ordinary variable condenser there are interposed between the plates to keep them spaced apart, washers 27 mounted on the rods 25 and made of a conducting material so that all the fixed plates are electrically connected. Similarly all the rotor plates are electrically united and means must be provided for insulating the fixed plates and the rotor plates from each other. That is, if the end members are constructed of metal, either set of plates, or both, must be insulated therefrom. I prefer to construct the end members of an insulating material but I do not limit myself to this construction.

In accordance with my invention I replace a number of the washers on rods 25 by washers made of insulating material 28 and I also construct the rods 25 of non-conducting material so that the fixed plates adjacent to the insulating washers are electrically disconnected and independent. he effect of this is to provide a number of adjacent fixed condensers, one side of each consituting at the same time one side of the adjacent condenser. To each one of the plates which is completely insulated (22 is attached an end of one of the wires 19 by soldering or by similar means. No connection is made with plate 22 which lies between the first insulating washer 28 and the first conducting washer 27. This plate 22 constitutes part of the condenser element which comprises the plates 22 electrically connected. It follows that no use is made of the fixed condenser lying between plate 22 and the adjacent plate 22. The connection between wires 19 and plates 22 as described in effect places a series of variable condensers in parallel with adjacent portions of the primary coil. The condenser unit 20 connected across the secondary coil in the usual manner as illustratively and diagrammatically shown at 29 in Figure 3.

the multiple capacities across the primary" portions is produced by the interposition between the fixed condenser plates 22 oi movable plates entirely disconnected from the primary e il. Thus a movement oftherotor alters the natureof the dielectric between plates 22 'and at the same time alters the size of the air gap between plates 22 and the rotor plates. Such a simultaneous control of condens rs in parallelwith both the primary and secondary windings has proved in practice to: be very effectual in harmoniously tuning both windings with correspondingly great improvements in selectivity and gor eral radio reception. I do not limit myself however to a utilization of my invention only-in connecteion with receiving sets.

Another feature of my device lies in the provision of means for setting the coil; at any desired angle relative to the condenser unit. a transformer in connection with similar transformers is most effectualif placed at an angle with respect to the plane passing through the centers of the transformers for the purpose of minimizing the linkage of flux between adjacent transform'ers In my device I provide projecting arms 31 pivotally attached at one end to the outside of one or the end members 21. These pivotal points of attachment are preferably near theedgeof the end member adjacent the straight edges of the plates and on opposite sides of va center line perpendicular to these edges.

The arms 31 are provided Wlil'l openings ad jacent their outer ends adapted to receive rods 32 extending therethroughand carried by and projecting radially from the outer, tube 1 1. The rods 32 are externally thread ed' at the ends projecting through the openings in the arms 31 to receive'knurled' nuts 33. Mounted on the rods and interposed between the arms 31 and the pointsof at- It-is well known that a coil used as tachment of the rods 32 to the tube 14 are a plurality of washer members 3e adapted to keep the tube 14 spaced away from the arms 31 when the nuts 33 are screwed up. tightly to bear against the faces of'arms 31. The pivotal connections between the arms 31 and the end member 21 are preferably made in a similar manner so that pins projecting from the end member and parallel to the pins 32 extend through openings "in the arms 31 and are threaded to receive tightening nuts 35. By loosening nuts 35 and 33 it is possible to swing the arms 31 in circular arcs having their centers at the axes of the pins. extending through nuts 35 and the inductance coil will accordingly change its angular position I do not limit myself to the specific construction I have described. For instance, the primary coil 15 may be tapped at any desired number of points and if a very delicate instrument is requireda connection 7 may be made between each turn of the primary coil and; a separate insulated fixed plate 22"; The means carried by the condenser for pivotally supporting the coil and locking the coil at any desired angle might consist for example of a single arm 31, and various other mechanical means might be substituted for those described without departing from the spirit of my invention.

-1. Radio apparatus of the character de scribed, comprising an induction coil having a primary winding and a secondary winding the primary winding being tapped to provide exposed portions to allow electrical connection to be made at spaced intervals, a variable plate condenser having a plurality of spaced, fixed plates and a plurality of movable rotor plates interposed between the fixed plates, certain adjacent fixed plates being electrically connected respectivcly with said exposed portions of the tapped primary and being insulatedfrom each other. I

2. Radio apparatus as claimed in claim 1, including parallel end members for said condenser having aligned bores, said fixed and rotor plates having bores alignedwith said first named bores, insulating means extending through said bores to support the plates and bind them together, and washers mounted on said means and interposed between said plates, all of which washers are electrical conductors except those between the plates electrically connected with the pri mary.

In testimony whereof-I have afiixed my signature. 7

AMBROSE H. ROSENTHAL. 

